Interpreting graphical representations, as part of graphical literacy, is becoming an increasingly important skill in various areas of everyday life. The results of the PISA study indicate insufficient mastery of this skill among Croatian students, necessitating a special focus on it. The aim of this research was to analyze different levels of understanding graphical representations among sixth-grade students. The study included 27 sixth-grade students from the same elementary school. The measuring instrument developed for the purposes of this research consisted of two types of graphical representations. The skill of interpreting graphical representations was tested with questions aimed at three levels of understanding - elementary level (data reading), intermediate level (data connecting) and advanced level (data generalization). The results were analyzed using IBM SPSS Statistics software. Students achieved the lowest number of correct answers at the advanced level of understanding graphical representations and the highest at the elementary level. The Friedman test showed that the differences in the number of correct answers among the different levels of understanding graphical representations were not statistically significant. The importance of this research lies in understanding the domains in which students struggle within the skill of interpreting graphical representations, as well as in highlighting the importance of direct and comprehensive teaching of this skill.